docs: def df_pdb_blast(self):
          """DataFrame: Get a dataframe of PDB BLAST results"""
          blast_results_pre_df = []
  
          for p in self.get_experimental_structures():
              for c in p.chains:
                  if hasattr(c, 'blast_results'):
                      # Summary dataframe
                      infodict = p.get_dict_with_chain(chain=c.id)['blast_results']
                      infodict['pdb_id'] = p.id
                      infodict['pdb_chain_id'] = c.id
                      blast_results_pre_df.append(infodict)
  
          cols = ['pdb_id', 'pdb_chain_id', 'hit_score', 'hit_evalue', 'hit_percent_similar',
                  'hit_percent_ident', 'hit_percent_gaps', 'hit_num_ident', 'hit_num_similar', 'hit_num_gaps']
          df = pd.DataFrame.from_records(blast_results_pre_df, columns=cols).set_index('pdb_id')
          return ssbio.utils.clean_df(df)